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Chris Lattner1811fca2004-01-05 05:06:33 +00006 <title>Source Level Debugging with LLVM</title>
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11<div class="doc_title">Source Level Debugging with LLVM</div>
12
Reid Spencerc3c4c4f2004-11-01 08:19:36 +000013<table class="layout" style="width:100%">
14 <tr class="layout">
15 <td class="left">
Chris Lattner1811fca2004-01-05 05:06:33 +000016<ul>
Misha Brukmanf91d9942004-05-12 19:21:57 +000017 <li><a href="#introduction">Introduction</a>
Chris Lattner1811fca2004-01-05 05:06:33 +000018 <ol>
19 <li><a href="#phil">Philosophy behind LLVM debugging information</a></li>
Jim Laskey5dcfd562006-03-23 17:54:33 +000020 <li><a href="#consumers">Debug information consumers</a></li>
Chris Lattner1811fca2004-01-05 05:06:33 +000021 <li><a href="#debugopt">Debugging optimized code</a></li>
Misha Brukmanf91d9942004-05-12 19:21:57 +000022 </ol></li>
Misha Brukmanf91d9942004-05-12 19:21:57 +000023 <li><a href="#format">Debugging information format</a>
Chris Lattner1811fca2004-01-05 05:06:33 +000024 <ol>
Jim Laskey14edc932006-03-14 18:08:46 +000025 <li><a href="#debug_info_descriptors">Debug information descriptors</a>
Chris Lattner1811fca2004-01-05 05:06:33 +000026 <ul>
Jim Laskey14edc932006-03-14 18:08:46 +000027 <li><a href="#format_compile_units">Compile unit descriptors</a></li>
Devang Patel59445db2010-03-09 00:44:10 +000028 <li><a href="#format_files">File descriptors</a></li>
Jim Laskey14edc932006-03-14 18:08:46 +000029 <li><a href="#format_global_variables">Global variable descriptors</a></li>
30 <li><a href="#format_subprograms">Subprogram descriptors</a></li>
Jim Laskey9dcffe72006-03-15 19:10:52 +000031 <li><a href="#format_blocks">Block descriptors</a></li>
Jim Laskey14edc932006-03-14 18:08:46 +000032 <li><a href="#format_basic_type">Basic type descriptors</a></li>
33 <li><a href="#format_derived_type">Derived type descriptors</a></li>
34 <li><a href="#format_composite_type">Composite type descriptors</a></li>
35 <li><a href="#format_subrange">Subrange descriptors</a></li>
36 <li><a href="#format_enumeration">Enumerator descriptors</a></li>
Jim Laskey5dcfd562006-03-23 17:54:33 +000037 <li><a href="#format_variables">Local variables</a></li>
Misha Brukmanf91d9942004-05-12 19:21:57 +000038 </ul></li>
Jim Laskey14edc932006-03-14 18:08:46 +000039 <li><a href="#format_common_intrinsics">Debugger intrinsic functions</a>
40 <ul>
Jim Laskey14edc932006-03-14 18:08:46 +000041 <li><a href="#format_common_declare">llvm.dbg.declare</a></li>
Victor Hernandez0b62cc62010-01-11 22:53:48 +000042 <li><a href="#format_common_value">llvm.dbg.value</a></li>
Jim Laskey14edc932006-03-14 18:08:46 +000043 </ul></li>
Misha Brukmanf91d9942004-05-12 19:21:57 +000044 </ol></li>
Devang Patel4da997b2009-11-25 23:28:01 +000045 <li><a href="#format_common_lifetime">Object lifetimes and scoping</a></li>
Misha Brukmanf91d9942004-05-12 19:21:57 +000046 <li><a href="#ccxx_frontend">C/C++ front-end specific debug information</a>
Chris Lattner1811fca2004-01-05 05:06:33 +000047 <ol>
Jim Laskey14edc932006-03-14 18:08:46 +000048 <li><a href="#ccxx_compile_units">C/C++ source file information</a></li>
49 <li><a href="#ccxx_global_variable">C/C++ global variable information</a></li>
50 <li><a href="#ccxx_subprogram">C/C++ function information</a></li>
51 <li><a href="#ccxx_basic_types">C/C++ basic types</a></li>
52 <li><a href="#ccxx_derived_types">C/C++ derived types</a></li>
53 <li><a href="#ccxx_composite_types">C/C++ struct/union types</a></li>
54 <li><a href="#ccxx_enumeration_types">C/C++ enumeration types</a></li>
Misha Brukmanf91d9942004-05-12 19:21:57 +000055 </ol></li>
Chris Lattner1811fca2004-01-05 05:06:33 +000056</ul>
Misha Brukmanf91d9942004-05-12 19:21:57 +000057</td>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +000058<td class="right">
Misha Brukman3c1f8e72004-05-12 21:26:16 +000059<img src="img/venusflytrap.jpg" alt="A leafy and green bug eater" width="247"
Misha Brukmanf91d9942004-05-12 19:21:57 +000060height="369">
61</td>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +000062</tr></table>
Misha Brukmanf91d9942004-05-12 19:21:57 +000063
Chris Lattner020e1fc2004-05-23 21:07:27 +000064<div class="doc_author">
Jim Laskey14edc932006-03-14 18:08:46 +000065 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
Jim Laskey6e8a2f42007-03-14 19:32:21 +000066 and <a href="mailto:jlaskey@mac.com">Jim Laskey</a></p>
Chris Lattner020e1fc2004-05-23 21:07:27 +000067</div>
68
Chris Lattner1811fca2004-01-05 05:06:33 +000069
70<!-- *********************************************************************** -->
Misha Brukmancda6a9b2004-12-09 20:27:37 +000071<div class="doc_section"><a name="introduction">Introduction</a></div>
72<!-- *********************************************************************** -->
Chris Lattner1811fca2004-01-05 05:06:33 +000073
74<div class="doc_text">
75
76<p>This document is the central repository for all information pertaining to
Bill Wendlinge9353d72009-05-17 05:52:39 +000077 debug information in LLVM. It describes the <a href="#format">actual format
78 that the LLVM debug information</a> takes, which is useful for those
79 interested in creating front-ends or dealing directly with the information.
Chris Lattnercb3f64f2009-07-18 21:47:15 +000080 Further, this document provides specific examples of what debug information
Bill Wendlinge9353d72009-05-17 05:52:39 +000081 for C/C++.</p>
Chris Lattner1811fca2004-01-05 05:06:33 +000082
83</div>
84
85<!-- ======================================================================= -->
86<div class="doc_subsection">
87 <a name="phil">Philosophy behind LLVM debugging information</a>
88</div>
89
90<div class="doc_text">
91
Misha Brukmanf91d9942004-05-12 19:21:57 +000092<p>The idea of the LLVM debugging information is to capture how the important
Bill Wendlinge9353d72009-05-17 05:52:39 +000093 pieces of the source-language's Abstract Syntax Tree map onto LLVM code.
94 Several design aspects have shaped the solution that appears here. The
95 important ones are:</p>
Chris Lattner1811fca2004-01-05 05:06:33 +000096
Misha Brukmanf91d9942004-05-12 19:21:57 +000097<ul>
Bill Wendlinge9353d72009-05-17 05:52:39 +000098 <li>Debugging information should have very little impact on the rest of the
99 compiler. No transformations, analyses, or code generators should need to
100 be modified because of debugging information.</li>
Chris Lattner1811fca2004-01-05 05:06:33 +0000101
Bill Wendlinge9353d72009-05-17 05:52:39 +0000102 <li>LLVM optimizations should interact in <a href="#debugopt">well-defined and
103 easily described ways</a> with the debugging information.</li>
Chris Lattner1811fca2004-01-05 05:06:33 +0000104
Bill Wendlinge9353d72009-05-17 05:52:39 +0000105 <li>Because LLVM is designed to support arbitrary programming languages,
106 LLVM-to-LLVM tools should not need to know anything about the semantics of
107 the source-level-language.</li>
Chris Lattner1811fca2004-01-05 05:06:33 +0000108
Bill Wendlinge9353d72009-05-17 05:52:39 +0000109 <li>Source-level languages are often <b>widely</b> different from one another.
110 LLVM should not put any restrictions of the flavor of the source-language,
111 and the debugging information should work with any language.</li>
Chris Lattner1811fca2004-01-05 05:06:33 +0000112
Bill Wendlinge9353d72009-05-17 05:52:39 +0000113 <li>With code generator support, it should be possible to use an LLVM compiler
114 to compile a program to native machine code and standard debugging
115 formats. This allows compatibility with traditional machine-code level
116 debuggers, like GDB or DBX.</li>
Misha Brukmanf91d9942004-05-12 19:21:57 +0000117</ul>
Chris Lattner1811fca2004-01-05 05:06:33 +0000118
Bill Wendlinge9353d72009-05-17 05:52:39 +0000119<p>The approach used by the LLVM implementation is to use a small set
120 of <a href="#format_common_intrinsics">intrinsic functions</a> to define a
121 mapping between LLVM program objects and the source-level objects. The
Devang Patel80ae3492009-08-28 23:24:31 +0000122 description of the source-level program is maintained in LLVM metadata
123 in an <a href="#ccxx_frontend">implementation-defined format</a>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000124 (the C/C++ front-end currently uses working draft 7 of
125 the <a href="http://www.eagercon.com/dwarf/dwarf3std.htm">DWARF 3
126 standard</a>).</p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000127
Jim Laskey14edc932006-03-14 18:08:46 +0000128<p>When a program is being debugged, a debugger interacts with the user and
Bill Wendlinge9353d72009-05-17 05:52:39 +0000129 turns the stored debug information into source-language specific information.
130 As such, a debugger must be aware of the source-language, and is thus tied to
131 a specific language or family of languages.</p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000132
133</div>
134
Chris Lattner1811fca2004-01-05 05:06:33 +0000135<!-- ======================================================================= -->
136<div class="doc_subsection">
Jim Laskey5dcfd562006-03-23 17:54:33 +0000137 <a name="consumers">Debug information consumers</a>
138</div>
139
140<div class="doc_text">
Bill Wendlinge9353d72009-05-17 05:52:39 +0000141
Jim Laskey5dcfd562006-03-23 17:54:33 +0000142<p>The role of debug information is to provide meta information normally
Bill Wendlinge9353d72009-05-17 05:52:39 +0000143 stripped away during the compilation process. This meta information provides
144 an LLVM user a relationship between generated code and the original program
145 source code.</p>
Jim Laskey5dcfd562006-03-23 17:54:33 +0000146
Chris Lattner904f2172010-04-05 04:11:11 +0000147<p>Currently, debug information is consumed by DwarfDebug to produce dwarf
Bill Wendlinge9353d72009-05-17 05:52:39 +0000148 information used by the gdb debugger. Other targets could use the same
149 information to produce stabs or other debug forms.</p>
Jim Laskey5dcfd562006-03-23 17:54:33 +0000150
151<p>It would also be reasonable to use debug information to feed profiling tools
Bill Wendlinge9353d72009-05-17 05:52:39 +0000152 for analysis of generated code, or, tools for reconstructing the original
153 source from generated code.</p>
Jim Laskey5dcfd562006-03-23 17:54:33 +0000154
155<p>TODO - expound a bit more.</p>
156
157</div>
158
159<!-- ======================================================================= -->
160<div class="doc_subsection">
Chris Lattner1811fca2004-01-05 05:06:33 +0000161 <a name="debugopt">Debugging optimized code</a>
162</div>
163
164<div class="doc_text">
Chris Lattner1811fca2004-01-05 05:06:33 +0000165
Misha Brukmanf91d9942004-05-12 19:21:57 +0000166<p>An extremely high priority of LLVM debugging information is to make it
Bill Wendlinge9353d72009-05-17 05:52:39 +0000167 interact well with optimizations and analysis. In particular, the LLVM debug
168 information provides the following guarantees:</p>
Misha Brukmanf91d9942004-05-12 19:21:57 +0000169
170<ul>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000171 <li>LLVM debug information <b>always provides information to accurately read
172 the source-level state of the program</b>, regardless of which LLVM
173 optimizations have been run, and without any modification to the
174 optimizations themselves. However, some optimizations may impact the
175 ability to modify the current state of the program with a debugger, such
176 as setting program variables, or calling functions that have been
177 deleted.</li>
Chris Lattner1811fca2004-01-05 05:06:33 +0000178
Bill Wendlinge9353d72009-05-17 05:52:39 +0000179 <li>LLVM optimizations gracefully interact with debugging information. If
180 they are not aware of debug information, they are automatically disabled
181 as necessary in the cases that would invalidate the debug info. This
182 retains the LLVM features, making it easy to write new
183 transformations.</li>
Chris Lattner1811fca2004-01-05 05:06:33 +0000184
Bill Wendlinge9353d72009-05-17 05:52:39 +0000185 <li>As desired, LLVM optimizations can be upgraded to be aware of the LLVM
186 debugging information, allowing them to update the debugging information
187 as they perform aggressive optimizations. This means that, with effort,
188 the LLVM optimizers could optimize debug code just as well as non-debug
189 code.</li>
Chris Lattner1811fca2004-01-05 05:06:33 +0000190
Bill Wendlinge9353d72009-05-17 05:52:39 +0000191 <li>LLVM debug information does not prevent many important optimizations from
192 happening (for example inlining, basic block reordering/merging/cleanup,
193 tail duplication, etc), further reducing the amount of the compiler that
194 eventually is "aware" of debugging information.</li>
Chris Lattner1811fca2004-01-05 05:06:33 +0000195
Bill Wendlinge9353d72009-05-17 05:52:39 +0000196 <li>LLVM debug information is automatically optimized along with the rest of
197 the program, using existing facilities. For example, duplicate
198 information is automatically merged by the linker, and unused information
199 is automatically removed.</li>
Misha Brukmanf91d9942004-05-12 19:21:57 +0000200</ul>
Chris Lattner1811fca2004-01-05 05:06:33 +0000201
Misha Brukmanf91d9942004-05-12 19:21:57 +0000202<p>Basically, the debug information allows you to compile a program with
Bill Wendlinge9353d72009-05-17 05:52:39 +0000203 "<tt>-O0 -g</tt>" and get full debug information, allowing you to arbitrarily
204 modify the program as it executes from a debugger. Compiling a program with
205 "<tt>-O3 -g</tt>" gives you full debug information that is always available
206 and accurate for reading (e.g., you get accurate stack traces despite tail
207 call elimination and inlining), but you might lose the ability to modify the
208 program and call functions where were optimized out of the program, or
209 inlined away completely.</p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000210
Misha Brukman39dcddf2008-12-16 02:54:22 +0000211<p><a href="TestingGuide.html#quicktestsuite">LLVM test suite</a> provides a
Bill Wendlinge9353d72009-05-17 05:52:39 +0000212 framework to test optimizer's handling of debugging information. It can be
213 run like this:</p>
Devang Patelb885a912008-11-21 19:35:57 +0000214
215<div class="doc_code">
216<pre>
217% cd llvm/projects/test-suite/MultiSource/Benchmarks # or some other level
218% make TEST=dbgopt
219</pre>
220</div>
221
Bill Wendlinge9353d72009-05-17 05:52:39 +0000222<p>This will test impact of debugging information on optimization passes. If
223 debugging information influences optimization passes then it will be reported
224 as a failure. See <a href="TestingGuide.html">TestingGuide</a> for more
225 information on LLVM test infrastructure and how to run various tests.</p>
Devang Patelb885a912008-11-21 19:35:57 +0000226
Chris Lattner1811fca2004-01-05 05:06:33 +0000227</div>
228
Chris Lattner1811fca2004-01-05 05:06:33 +0000229<!-- *********************************************************************** -->
230<div class="doc_section">
Chris Lattner941515c2004-01-06 05:31:32 +0000231 <a name="format">Debugging information format</a>
Chris Lattner1811fca2004-01-05 05:06:33 +0000232</div>
233<!-- *********************************************************************** -->
234
235<div class="doc_text">
236
237<p>LLVM debugging information has been carefully designed to make it possible
Bill Wendlinge9353d72009-05-17 05:52:39 +0000238 for the optimizer to optimize the program and debugging information without
239 necessarily having to know anything about debugging information. In
John Criswell2a4b0802010-03-17 15:01:50 +0000240 particular, the use of metadata avoids duplicated debugging information from
Devang Patel80ae3492009-08-28 23:24:31 +0000241 the beginning, and the global dead code elimination pass automatically
242 deletes debugging information for a function if it decides to delete the
243 function. </p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000244
245<p>To do this, most of the debugging information (descriptors for types,
Bill Wendlinge9353d72009-05-17 05:52:39 +0000246 variables, functions, source files, etc) is inserted by the language
Devang Patel80ae3492009-08-28 23:24:31 +0000247 front-end in the form of LLVM metadata. </p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000248
Jim Laskey14edc932006-03-14 18:08:46 +0000249<p>Debug information is designed to be agnostic about the target debugger and
Bill Wendlinge9353d72009-05-17 05:52:39 +0000250 debugging information representation (e.g. DWARF/Stabs/etc). It uses a
Devang Patel80ae3492009-08-28 23:24:31 +0000251 generic pass to decode the information that represents variables, types,
252 functions, namespaces, etc: this allows for arbitrary source-language
253 semantics and type-systems to be used, as long as there is a module
254 written for the target debugger to interpret the information. </p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000255
Misha Brukmanf91d9942004-05-12 19:21:57 +0000256<p>To provide basic functionality, the LLVM debugger does have to make some
Bill Wendlinge9353d72009-05-17 05:52:39 +0000257 assumptions about the source-level language being debugged, though it keeps
258 these to a minimum. The only common features that the LLVM debugger assumes
Devang Patel59445db2010-03-09 00:44:10 +0000259 exist are <a href="#format_files">source files</a>,
Bill Wendlinge9353d72009-05-17 05:52:39 +0000260 and <a href="#format_global_variables">program objects</a>. These abstract
261 objects are used by a debugger to form stack traces, show information about
262 local variables, etc.</p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000263
264<p>This section of the documentation first describes the representation aspects
Bill Wendlinge9353d72009-05-17 05:52:39 +0000265 common to any source-language. The <a href="#ccxx_frontend">next section</a>
266 describes the data layout conventions used by the C and C++ front-ends.</p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000267
268</div>
269
270<!-- ======================================================================= -->
271<div class="doc_subsection">
Jim Laskey14edc932006-03-14 18:08:46 +0000272 <a name="debug_info_descriptors">Debug information descriptors</a>
Chris Lattner1811fca2004-01-05 05:06:33 +0000273</div>
274
275<div class="doc_text">
Bill Wendlinge9353d72009-05-17 05:52:39 +0000276
Jim Laskey14edc932006-03-14 18:08:46 +0000277<p>In consideration of the complexity and volume of debug information, LLVM
Devang Patel80ae3492009-08-28 23:24:31 +0000278 provides a specification for well formed debug descriptors. </p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000279
Jim Laskey14edc932006-03-14 18:08:46 +0000280<p>Consumers of LLVM debug information expect the descriptors for program
Bill Wendlinge9353d72009-05-17 05:52:39 +0000281 objects to start in a canonical format, but the descriptors can include
282 additional information appended at the end that is source-language
283 specific. All LLVM debugging information is versioned, allowing backwards
284 compatibility in the case that the core structures need to change in some
285 way. Also, all debugging information objects start with a tag to indicate
286 what type of object it is. The source-language is allowed to define its own
287 objects, by using unreserved tag numbers. We recommend using with tags in
Benjamin Kramer0f420382009-10-12 14:46:08 +0000288 the range 0x1000 through 0x2000 (there is a defined enum DW_TAG_user_base =
Bill Wendlinge9353d72009-05-17 05:52:39 +0000289 0x1000.)</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000290
Devang Patel80ae3492009-08-28 23:24:31 +0000291<p>The fields of debug descriptors used internally by LLVM
Nick Lewyckya87014f2010-03-31 07:50:17 +0000292 are restricted to only the simple data types <tt>i32</tt>, <tt>i1</tt>,
293 <tt>float</tt>, <tt>double</tt>, <tt>mdstring</tt> and <tt>mdnode</tt>. </p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000294
Bill Wendlinge9353d72009-05-17 05:52:39 +0000295<div class="doc_code">
Misha Brukmanf91d9942004-05-12 19:21:57 +0000296<pre>
Devang Patel80ae3492009-08-28 23:24:31 +0000297!1 = metadata !{
Nick Lewyckya87014f2010-03-31 07:50:17 +0000298 i32, ;; A tag
Bill Wendlinge9353d72009-05-17 05:52:39 +0000299 ...
300}
Misha Brukmanf91d9942004-05-12 19:21:57 +0000301</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000302</div>
Chris Lattner1811fca2004-01-05 05:06:33 +0000303
Jim Laskeyb2ff2d42006-06-16 13:14:03 +0000304<p><a name="LLVMDebugVersion">The first field of a descriptor is always an
Nick Lewyckya87014f2010-03-31 07:50:17 +0000305 <tt>i32</tt> containing a tag value identifying the content of the
Bill Wendlinge9353d72009-05-17 05:52:39 +0000306 descriptor. The remaining fields are specific to the descriptor. The values
307 of tags are loosely bound to the tag values of DWARF information entries.
308 However, that does not restrict the use of the information supplied to DWARF
309 targets. To facilitate versioning of debug information, the tag is augmented
Nick Lewyckya87014f2010-03-31 07:50:17 +0000310 with the current debug version (LLVMDebugVersion = 8 &lt;&lt; 16 or 0x80000 or
Devang Patel59445db2010-03-09 00:44:10 +0000311 524288.)</a></p>
Jim Laskey14edc932006-03-14 18:08:46 +0000312
Jim Laskeyb2ff2d42006-06-16 13:14:03 +0000313<p>The details of the various descriptors follow.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000314
315</div>
316
317<!-- ======================================================================= -->
318<div class="doc_subsubsection">
Jim Laskey14edc932006-03-14 18:08:46 +0000319 <a name="format_compile_units">Compile unit descriptors</a>
320</div>
321
322<div class="doc_text">
323
Bill Wendlinge9353d72009-05-17 05:52:39 +0000324<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +0000325<pre>
Devang Patel80ae3492009-08-28 23:24:31 +0000326!0 = metadata !{
327 i32, ;; Tag = 17 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
328 ;; (DW_TAG_compile_unit)
329 i32, ;; Unused field.
330 i32, ;; DWARF language identifier (ex. DW_LANG_C89)
331 metadata, ;; Source file name
332 metadata, ;; Source file directory (includes trailing slash)
333 metadata ;; Producer (ex. "4.0.1 LLVM (LLVM research group)")
334 i1, ;; True if this is a main compile unit.
335 i1, ;; True if this is optimized.
336 metadata, ;; Flags
337 i32 ;; Runtime version
Bill Wendlinge9353d72009-05-17 05:52:39 +0000338}
Jim Laskey14edc932006-03-14 18:08:46 +0000339</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000340</div>
Jim Laskey14edc932006-03-14 18:08:46 +0000341
Bill Wendlinge9353d72009-05-17 05:52:39 +0000342<p>These descriptors contain a source language ID for the file (we use the DWARF
343 3.0 ID numbers, such as <tt>DW_LANG_C89</tt>, <tt>DW_LANG_C_plus_plus</tt>,
344 <tt>DW_LANG_Cobol74</tt>, etc), three strings describing the filename,
345 working directory of the compiler, and an identifier string for the compiler
346 that produced it.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000347
Bill Wendlinge9353d72009-05-17 05:52:39 +0000348<p>Compile unit descriptors provide the root context for objects declared in a
Devang Patel59445db2010-03-09 00:44:10 +0000349 specific compilation unit. File descriptors are defined using this context.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000350
Devang Patel59445db2010-03-09 00:44:10 +0000351</div>
352
353<!-- ======================================================================= -->
354<div class="doc_subsubsection">
355 <a name="format_files">File descriptors</a>
356</div>
357
358<div class="doc_text">
359
360<div class="doc_code">
361<pre>
362!0 = metadata !{
363 i32, ;; Tag = 41 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
364 ;; (DW_TAG_file_type)
365 metadata, ;; Source file name
366 metadata, ;; Source file directory (includes trailing slash)
367 metadata ;; Reference to compile unit where defined
368}
369</pre>
370</div>
371
John Criswell2a4b0802010-03-17 15:01:50 +0000372<p>These descriptors contain information for a file. Global variables and top
Devang Patel59445db2010-03-09 00:44:10 +0000373 level functions would be defined using this context.k File descriptors also
374 provide context for source line correspondence. </p>
375
376<p>Each input file is encoded as a separate file descriptor in LLVM debugging
377 information output. Each file descriptor would be defined using a
378 compile unit. </p>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000379
Jim Laskey14edc932006-03-14 18:08:46 +0000380</div>
381
382<!-- ======================================================================= -->
383<div class="doc_subsubsection">
384 <a name="format_global_variables">Global variable descriptors</a>
385</div>
386
387<div class="doc_text">
388
Bill Wendlinge9353d72009-05-17 05:52:39 +0000389<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +0000390<pre>
Devang Patel80ae3492009-08-28 23:24:31 +0000391!1 = metadata !{
392 i32, ;; Tag = 52 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
393 ;; (DW_TAG_variable)
394 i32, ;; Unused field.
395 metadata, ;; Reference to context descriptor
396 metadata, ;; Name
397 metadata, ;; Display name (fully qualified C++ name)
398 metadata, ;; MIPS linkage name (for C++)
Devang Patel59445db2010-03-09 00:44:10 +0000399 metadata, ;; Reference to file where defined
Devang Patel80ae3492009-08-28 23:24:31 +0000400 i32, ;; Line number where defined
401 metadata, ;; Reference to type descriptor
402 i1, ;; True if the global is local to compile unit (static)
403 i1, ;; True if the global is defined in the compile unit (not extern)
404 { }* ;; Reference to the global variable
Bill Wendlinge9353d72009-05-17 05:52:39 +0000405}
Jim Laskey14edc932006-03-14 18:08:46 +0000406</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000407</div>
Jim Laskey14edc932006-03-14 18:08:46 +0000408
409<p>These descriptors provide debug information about globals variables. The
410provide details such as name, type and where the variable is defined.</p>
411
412</div>
413
414<!-- ======================================================================= -->
415<div class="doc_subsubsection">
416 <a name="format_subprograms">Subprogram descriptors</a>
417</div>
418
419<div class="doc_text">
420
Bill Wendlinge9353d72009-05-17 05:52:39 +0000421<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +0000422<pre>
Devang Patel80ae3492009-08-28 23:24:31 +0000423!2 = metadata !{
424 i32, ;; Tag = 46 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
425 ;; (DW_TAG_subprogram)
426 i32, ;; Unused field.
427 metadata, ;; Reference to context descriptor
428 metadata, ;; Name
429 metadata, ;; Display name (fully qualified C++ name)
430 metadata, ;; MIPS linkage name (for C++)
Devang Patel59445db2010-03-09 00:44:10 +0000431 metadata, ;; Reference to file where defined
Devang Patel80ae3492009-08-28 23:24:31 +0000432 i32, ;; Line number where defined
433 metadata, ;; Reference to type descriptor
434 i1, ;; True if the global is local to compile unit (static)
435 i1 ;; True if the global is defined in the compile unit (not extern)
Bill Wendlinge9353d72009-05-17 05:52:39 +0000436}
Jim Laskey14edc932006-03-14 18:08:46 +0000437</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000438</div>
Jim Laskey14edc932006-03-14 18:08:46 +0000439
440<p>These descriptors provide debug information about functions, methods and
Bill Wendlinge9353d72009-05-17 05:52:39 +0000441 subprograms. They provide details such as name, return types and the source
442 location where the subprogram is defined.</p>
Jim Laskey9dcffe72006-03-15 19:10:52 +0000443
444</div>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000445
Jim Laskey9dcffe72006-03-15 19:10:52 +0000446<!-- ======================================================================= -->
447<div class="doc_subsubsection">
448 <a name="format_blocks">Block descriptors</a>
449</div>
450
451<div class="doc_text">
452
Bill Wendlinge9353d72009-05-17 05:52:39 +0000453<div class="doc_code">
Jim Laskey9dcffe72006-03-15 19:10:52 +0000454<pre>
Devang Patel80ae3492009-08-28 23:24:31 +0000455!3 = metadata !{
456 i32, ;; Tag = 13 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
457 metadata ;; Reference to context descriptor
Bill Wendlinge9353d72009-05-17 05:52:39 +0000458}
Jim Laskey9dcffe72006-03-15 19:10:52 +0000459</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000460</div>
Jim Laskey9dcffe72006-03-15 19:10:52 +0000461
462<p>These descriptors provide debug information about nested blocks within a
Bill Wendlinge9353d72009-05-17 05:52:39 +0000463 subprogram. The array of member descriptors is used to define local
464 variables and deeper nested blocks.</p>
Jim Laskey9dcffe72006-03-15 19:10:52 +0000465
Jim Laskey14edc932006-03-14 18:08:46 +0000466</div>
467
468<!-- ======================================================================= -->
469<div class="doc_subsubsection">
470 <a name="format_basic_type">Basic type descriptors</a>
471</div>
472
473<div class="doc_text">
474
Bill Wendlinge9353d72009-05-17 05:52:39 +0000475<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +0000476<pre>
Devang Patel80ae3492009-08-28 23:24:31 +0000477!4 = metadata !{
478 i32, ;; Tag = 36 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
479 ;; (DW_TAG_base_type)
480 metadata, ;; Reference to context (typically a compile unit)
481 metadata, ;; Name (may be "" for anonymous types)
Devang Patel59445db2010-03-09 00:44:10 +0000482 metadata, ;; Reference to file where defined (may be NULL)
Devang Patel80ae3492009-08-28 23:24:31 +0000483 i32, ;; Line number where defined (may be 0)
484 i64, ;; Size in bits
485 i64, ;; Alignment in bits
486 i64, ;; Offset in bits
487 i32, ;; Flags
488 i32 ;; DWARF type encoding
Bill Wendlinge9353d72009-05-17 05:52:39 +0000489}
Jim Laskey14edc932006-03-14 18:08:46 +0000490</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000491</div>
Jim Laskey14edc932006-03-14 18:08:46 +0000492
493<p>These descriptors define primitive types used in the code. Example int, bool
Bill Wendlinge9353d72009-05-17 05:52:39 +0000494 and float. The context provides the scope of the type, which is usually the
495 top level. Since basic types are not usually user defined the compile unit
496 and line number can be left as NULL and 0. The size, alignment and offset
497 are expressed in bits and can be 64 bit values. The alignment is used to
498 round the offset when embedded in a
499 <a href="#format_composite_type">composite type</a> (example to keep float
500 doubles on 64 bit boundaries.) The offset is the bit offset if embedded in
501 a <a href="#format_composite_type">composite type</a>.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000502
503<p>The type encoding provides the details of the type. The values are typically
Bill Wendlinge9353d72009-05-17 05:52:39 +0000504 one of the following:</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000505
Bill Wendlinge9353d72009-05-17 05:52:39 +0000506<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +0000507<pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000508DW_ATE_address = 1
509DW_ATE_boolean = 2
510DW_ATE_float = 4
511DW_ATE_signed = 5
512DW_ATE_signed_char = 6
513DW_ATE_unsigned = 7
514DW_ATE_unsigned_char = 8
Jim Laskey14edc932006-03-14 18:08:46 +0000515</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000516</div>
Jim Laskey14edc932006-03-14 18:08:46 +0000517
518</div>
519
520<!-- ======================================================================= -->
521<div class="doc_subsubsection">
522 <a name="format_derived_type">Derived type descriptors</a>
523</div>
524
525<div class="doc_text">
526
Bill Wendlinge9353d72009-05-17 05:52:39 +0000527<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +0000528<pre>
Devang Patel80ae3492009-08-28 23:24:31 +0000529!5 = metadata !{
530 i32, ;; Tag (see below)
531 metadata, ;; Reference to context
532 metadata, ;; Name (may be "" for anonymous types)
Devang Patel59445db2010-03-09 00:44:10 +0000533 metadata, ;; Reference to file where defined (may be NULL)
Devang Patel80ae3492009-08-28 23:24:31 +0000534 i32, ;; Line number where defined (may be 0)
535 i32, ;; Size in bits
536 i32, ;; Alignment in bits
537 i32, ;; Offset in bits
538 metadata ;; Reference to type derived from
Bill Wendlinge9353d72009-05-17 05:52:39 +0000539}
Jim Laskey14edc932006-03-14 18:08:46 +0000540</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000541</div>
Jim Laskey14edc932006-03-14 18:08:46 +0000542
543<p>These descriptors are used to define types derived from other types. The
544value of the tag varies depending on the meaning. The following are possible
Misha Brukman39dcddf2008-12-16 02:54:22 +0000545tag values:</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000546
Bill Wendlinge9353d72009-05-17 05:52:39 +0000547<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +0000548<pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000549DW_TAG_formal_parameter = 5
550DW_TAG_member = 13
551DW_TAG_pointer_type = 15
552DW_TAG_reference_type = 16
553DW_TAG_typedef = 22
554DW_TAG_const_type = 38
555DW_TAG_volatile_type = 53
556DW_TAG_restrict_type = 55
Jim Laskey14edc932006-03-14 18:08:46 +0000557</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000558</div>
Jim Laskey14edc932006-03-14 18:08:46 +0000559
Bill Wendlinge9353d72009-05-17 05:52:39 +0000560<p><tt>DW_TAG_member</tt> is used to define a member of
561 a <a href="#format_composite_type">composite type</a>
562 or <a href="#format_subprograms">subprogram</a>. The type of the member is
563 the <a href="#format_derived_type">derived
564 type</a>. <tt>DW_TAG_formal_parameter</tt> is used to define a member which
565 is a formal argument of a subprogram.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000566
Bill Wendlinge9353d72009-05-17 05:52:39 +0000567<p><tt>DW_TAG_typedef</tt> is used to provide a name for the derived type.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000568
Bill Wendlinge9353d72009-05-17 05:52:39 +0000569<p><tt>DW_TAG_pointer_type</tt>,<tt>DW_TAG_reference_type</tt>,
570 <tt>DW_TAG_const_type</tt>, <tt>DW_TAG_volatile_type</tt>
571 and <tt>DW_TAG_restrict_type</tt> are used to qualify
572 the <a href="#format_derived_type">derived type</a>. </p>
Jim Laskey14edc932006-03-14 18:08:46 +0000573
574<p><a href="#format_derived_type">Derived type</a> location can be determined
Bill Wendlinge9353d72009-05-17 05:52:39 +0000575 from the compile unit and line number. The size, alignment and offset are
576 expressed in bits and can be 64 bit values. The alignment is used to round
577 the offset when embedded in a <a href="#format_composite_type">composite
578 type</a> (example to keep float doubles on 64 bit boundaries.) The offset is
579 the bit offset if embedded in a <a href="#format_composite_type">composite
580 type</a>.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000581
582<p>Note that the <tt>void *</tt> type is expressed as a
Bill Wendlinge9353d72009-05-17 05:52:39 +0000583 <tt>llvm.dbg.derivedtype.type</tt> with tag of <tt>DW_TAG_pointer_type</tt>
584 and <tt>NULL</tt> derived type.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000585
586</div>
587
588<!-- ======================================================================= -->
589<div class="doc_subsubsection">
590 <a name="format_composite_type">Composite type descriptors</a>
591</div>
592
593<div class="doc_text">
594
Bill Wendlinge9353d72009-05-17 05:52:39 +0000595<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +0000596<pre>
Devang Patel80ae3492009-08-28 23:24:31 +0000597!6 = metadata !{
598 i32, ;; Tag (see below)
599 metadata, ;; Reference to context
600 metadata, ;; Name (may be "" for anonymous types)
Devang Patel59445db2010-03-09 00:44:10 +0000601 metadata, ;; Reference to file where defined (may be NULL)
Devang Patel80ae3492009-08-28 23:24:31 +0000602 i32, ;; Line number where defined (may be 0)
603 i64, ;; Size in bits
604 i64, ;; Alignment in bits
605 i64, ;; Offset in bits
606 i32, ;; Flags
607 metadata, ;; Reference to type derived from
608 metadata, ;; Reference to array of member descriptors
609 i32 ;; Runtime languages
Bill Wendlinge9353d72009-05-17 05:52:39 +0000610}
Jim Laskey14edc932006-03-14 18:08:46 +0000611</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000612</div>
Jim Laskey14edc932006-03-14 18:08:46 +0000613
614<p>These descriptors are used to define types that are composed of 0 or more
615elements. The value of the tag varies depending on the meaning. The following
Misha Brukman39dcddf2008-12-16 02:54:22 +0000616are possible tag values:</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000617
Bill Wendlinge9353d72009-05-17 05:52:39 +0000618<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +0000619<pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000620DW_TAG_array_type = 1
621DW_TAG_enumeration_type = 4
622DW_TAG_structure_type = 19
623DW_TAG_union_type = 23
624DW_TAG_vector_type = 259
Bruno Cardoso Lopes9d809ca2009-05-29 17:08:57 +0000625DW_TAG_subroutine_type = 21
626DW_TAG_inheritance = 28
Jim Laskey14edc932006-03-14 18:08:46 +0000627</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000628</div>
Jim Laskey14edc932006-03-14 18:08:46 +0000629
Jim Laskey19f964e2006-06-15 20:51:43 +0000630<p>The vector flag indicates that an array type is a native packed vector.</p>
631
Jim Laskeyb2ff2d42006-06-16 13:14:03 +0000632<p>The members of array types (tag = <tt>DW_TAG_array_type</tt>) or vector types
Bill Wendlinge9353d72009-05-17 05:52:39 +0000633 (tag = <tt>DW_TAG_vector_type</tt>) are <a href="#format_subrange">subrange
634 descriptors</a>, each representing the range of subscripts at that level of
635 indexing.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000636
637<p>The members of enumeration types (tag = <tt>DW_TAG_enumeration_type</tt>) are
Bill Wendlinge9353d72009-05-17 05:52:39 +0000638 <a href="#format_enumeration">enumerator descriptors</a>, each representing
639 the definition of enumeration value for the set.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000640
641<p>The members of structure (tag = <tt>DW_TAG_structure_type</tt>) or union (tag
Bill Wendlinge9353d72009-05-17 05:52:39 +0000642 = <tt>DW_TAG_union_type</tt>) types are any one of
643 the <a href="#format_basic_type">basic</a>,
644 <a href="#format_derived_type">derived</a>
645 or <a href="#format_composite_type">composite</a> type descriptors, each
646 representing a field member of the structure or union.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000647
Jim Laskey4771cca2006-08-21 21:21:06 +0000648<p>For C++ classes (tag = <tt>DW_TAG_structure_type</tt>), member descriptors
Bill Wendlinge9353d72009-05-17 05:52:39 +0000649 provide information about base classes, static members and member
650 functions. If a member is a <a href="#format_derived_type">derived type
651 descriptor</a> and has a tag of <tt>DW_TAG_inheritance</tt>, then the type
652 represents a base class. If the member of is
653 a <a href="#format_global_variables">global variable descriptor</a> then it
654 represents a static member. And, if the member is
655 a <a href="#format_subprograms">subprogram descriptor</a> then it represents
656 a member function. For static members and member
657 functions, <tt>getName()</tt> returns the members link or the C++ mangled
658 name. <tt>getDisplayName()</tt> the simplied version of the name.</p>
Jim Laskey4771cca2006-08-21 21:21:06 +0000659
Bill Wendlinge9353d72009-05-17 05:52:39 +0000660<p>The first member of subroutine (tag = <tt>DW_TAG_subroutine_type</tt>) type
661 elements is the return type for the subroutine. The remaining elements are
662 the formal arguments to the subroutine.</p>
Jim Laskey4810c262006-06-20 21:13:20 +0000663
Jim Laskey14edc932006-03-14 18:08:46 +0000664<p><a href="#format_composite_type">Composite type</a> location can be
Bill Wendlinge9353d72009-05-17 05:52:39 +0000665 determined from the compile unit and line number. The size, alignment and
666 offset are expressed in bits and can be 64 bit values. The alignment is used
667 to round the offset when embedded in
668 a <a href="#format_composite_type">composite type</a> (as an example, to keep
669 float doubles on 64 bit boundaries.) The offset is the bit offset if embedded
670 in a <a href="#format_composite_type">composite type</a>.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000671
672</div>
673
674<!-- ======================================================================= -->
675<div class="doc_subsubsection">
676 <a name="format_subrange">Subrange descriptors</a>
677</div>
678
679<div class="doc_text">
680
Bill Wendlinge9353d72009-05-17 05:52:39 +0000681<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +0000682<pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000683%<a href="#format_subrange">llvm.dbg.subrange.type</a> = type {
684 i32, ;; Tag = 33 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subrange_type)
685 i64, ;; Low value
686 i64 ;; High value
687}
Jim Laskey14edc932006-03-14 18:08:46 +0000688</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000689</div>
Jim Laskey14edc932006-03-14 18:08:46 +0000690
691<p>These descriptors are used to define ranges of array subscripts for an array
Bill Wendlinge9353d72009-05-17 05:52:39 +0000692 <a href="#format_composite_type">composite type</a>. The low value defines
693 the lower bounds typically zero for C/C++. The high value is the upper
694 bounds. Values are 64 bit. High - low + 1 is the size of the array. If low
695 == high the array will be unbounded.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000696
697</div>
698
699<!-- ======================================================================= -->
700<div class="doc_subsubsection">
701 <a name="format_enumeration">Enumerator descriptors</a>
702</div>
703
704<div class="doc_text">
705
Bill Wendlinge9353d72009-05-17 05:52:39 +0000706<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +0000707<pre>
Devang Patel80ae3492009-08-28 23:24:31 +0000708!6 = metadata !{
709 i32, ;; Tag = 40 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
710 ;; (DW_TAG_enumerator)
711 metadata, ;; Name
712 i64 ;; Value
Bill Wendlinge9353d72009-05-17 05:52:39 +0000713}
Jim Laskey14edc932006-03-14 18:08:46 +0000714</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000715</div>
Jim Laskey14edc932006-03-14 18:08:46 +0000716
Bill Wendlinge9353d72009-05-17 05:52:39 +0000717<p>These descriptors are used to define members of an
718 enumeration <a href="#format_composite_type">composite type</a>, it
719 associates the name to the value.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000720
721</div>
722
723<!-- ======================================================================= -->
Jim Laskey5dcfd562006-03-23 17:54:33 +0000724<div class="doc_subsubsection">
725 <a name="format_variables">Local variables</a>
726</div>
727
728<div class="doc_text">
Bill Wendlinge9353d72009-05-17 05:52:39 +0000729
730<div class="doc_code">
Jim Laskey5dcfd562006-03-23 17:54:33 +0000731<pre>
Devang Patel80ae3492009-08-28 23:24:31 +0000732!7 = metadata !{
733 i32, ;; Tag (see below)
734 metadata, ;; Context
735 metadata, ;; Name
Devang Patel59445db2010-03-09 00:44:10 +0000736 metadata, ;; Reference to file where defined
Devang Patel80ae3492009-08-28 23:24:31 +0000737 i32, ;; Line number where defined
738 metadata ;; Type descriptor
Bill Wendlinge9353d72009-05-17 05:52:39 +0000739}
Jim Laskey5dcfd562006-03-23 17:54:33 +0000740</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000741</div>
Jim Laskey5dcfd562006-03-23 17:54:33 +0000742
743<p>These descriptors are used to define variables local to a sub program. The
Bill Wendlinge9353d72009-05-17 05:52:39 +0000744 value of the tag depends on the usage of the variable:</p>
Jim Laskey5dcfd562006-03-23 17:54:33 +0000745
Bill Wendlinge9353d72009-05-17 05:52:39 +0000746<div class="doc_code">
Jim Laskey5dcfd562006-03-23 17:54:33 +0000747<pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000748DW_TAG_auto_variable = 256
749DW_TAG_arg_variable = 257
750DW_TAG_return_variable = 258
Jim Laskey5dcfd562006-03-23 17:54:33 +0000751</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000752</div>
Jim Laskey5dcfd562006-03-23 17:54:33 +0000753
754<p>An auto variable is any variable declared in the body of the function. An
Bill Wendlinge9353d72009-05-17 05:52:39 +0000755 argument variable is any variable that appears as a formal argument to the
756 function. A return variable is used to track the result of a function and
757 has no source correspondent.</p>
Jim Laskey5dcfd562006-03-23 17:54:33 +0000758
Jim Laskey3481e122006-03-24 09:20:27 +0000759<p>The context is either the subprogram or block where the variable is defined.
Bill Wendlinge9353d72009-05-17 05:52:39 +0000760 Name the source variable name. Compile unit and line indicate where the
761 variable was defined. Type descriptor defines the declared type of the
762 variable.</p>
Jim Laskey5dcfd562006-03-23 17:54:33 +0000763
764</div>
765
766<!-- ======================================================================= -->
Chris Lattner1811fca2004-01-05 05:06:33 +0000767<div class="doc_subsection">
Jim Laskey14edc932006-03-14 18:08:46 +0000768 <a name="format_common_intrinsics">Debugger intrinsic functions</a>
769</div>
770
771<div class="doc_text">
772
773<p>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
Bill Wendlinge9353d72009-05-17 05:52:39 +0000774 provide debug information at various points in generated code.</p>
Jim Laskey14edc932006-03-14 18:08:46 +0000775
776</div>
777
778<!-- ======================================================================= -->
779<div class="doc_subsubsection">
Jim Laskey14edc932006-03-14 18:08:46 +0000780 <a name="format_common_declare">llvm.dbg.declare</a>
781</div>
782
783<div class="doc_text">
784<pre>
Devang Patel80ae3492009-08-28 23:24:31 +0000785 void %<a href="#format_common_declare">llvm.dbg.declare</a>( { } *, metadata )
Jim Laskey14edc932006-03-14 18:08:46 +0000786</pre>
787
Jim Laskey3481e122006-03-24 09:20:27 +0000788<p>This intrinsic provides information about a local element (ex. variable.) The
Bill Wendlinge9353d72009-05-17 05:52:39 +0000789 first argument is the alloca for the variable, cast to a <tt>{ }*</tt>. The
790 second argument is
791 the <tt>%<a href="#format_variables">llvm.dbg.variable</a></tt> containing
Devang Patel80ae3492009-08-28 23:24:31 +0000792 the description of the variable. </p>
Jim Laskey14edc932006-03-14 18:08:46 +0000793
794</div>
795
796<!-- ======================================================================= -->
Victor Hernandez0b62cc62010-01-11 22:53:48 +0000797<div class="doc_subsubsection">
798 <a name="format_common_value">llvm.dbg.value</a>
799</div>
800
801<div class="doc_text">
802<pre>
803 void %<a href="#format_common_value">llvm.dbg.value</a>( metadata, i64, metadata )
804</pre>
805
806<p>This intrinsic provides information when a user source variable is set to a
807 new value. The first argument is the new value (wrapped as metadata). The
808 second argument is the offset in the user source variable where the new value
809 is written. The third argument is
810 the <tt>%<a href="#format_variables">llvm.dbg.variable</a></tt> containing
811 the description of the user source variable. </p>
812
813</div>
814
815<!-- ======================================================================= -->
Jim Laskey14edc932006-03-14 18:08:46 +0000816<div class="doc_subsection">
Chris Lattner941515c2004-01-06 05:31:32 +0000817 <a name="format_common_lifetime">Object lifetimes and scoping</a>
Chris Lattner1811fca2004-01-05 05:06:33 +0000818</div>
819
820<div class="doc_text">
Bill Wendling991b84e2009-12-01 00:53:11 +0000821<p>In many languages, the local variables in functions can have their lifetimes
822 or scopes limited to a subset of a function. In the C family of languages,
Bill Wendlinge9353d72009-05-17 05:52:39 +0000823 for example, variables are only live (readable and writable) within the
824 source block that they are defined in. In functional languages, values are
825 only readable after they have been defined. Though this is a very obvious
Bill Wendling991b84e2009-12-01 00:53:11 +0000826 concept, it is non-trivial to model in LLVM, because it has no notion of
Bill Wendlinge9353d72009-05-17 05:52:39 +0000827 scoping in this sense, and does not want to be tied to a language's scoping
828 rules.</p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000829
Bill Wendling991b84e2009-12-01 00:53:11 +0000830<p>In order to handle this, the LLVM debug format uses the metadata attached to
Nick Lewyckya87014f2010-03-31 07:50:17 +0000831 llvm instructions to encode line number and scoping information. Consider
832 the following C fragment, for example:</p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000833
Bill Wendlinge9353d72009-05-17 05:52:39 +0000834<div class="doc_code">
Misha Brukmanf91d9942004-05-12 19:21:57 +0000835<pre>
Chris Lattner1811fca2004-01-05 05:06:33 +00008361. void foo() {
Devang Patel4da997b2009-11-25 23:28:01 +00008372. int X = 21;
8383. int Y = 22;
Chris Lattner1811fca2004-01-05 05:06:33 +00008394. {
Devang Patel4da997b2009-11-25 23:28:01 +00008405. int Z = 23;
8416. Z = X;
Chris Lattner1811fca2004-01-05 05:06:33 +00008427. }
Devang Patel4da997b2009-11-25 23:28:01 +00008438. X = Y;
Chris Lattner1811fca2004-01-05 05:06:33 +00008449. }
Misha Brukmanf91d9942004-05-12 19:21:57 +0000845</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000846</div>
Chris Lattner1811fca2004-01-05 05:06:33 +0000847
Jim Laskey14edc932006-03-14 18:08:46 +0000848<p>Compiled to LLVM, this function would be represented like this:</p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000849
Bill Wendlinge9353d72009-05-17 05:52:39 +0000850<div class="doc_code">
Misha Brukmanf91d9942004-05-12 19:21:57 +0000851<pre>
Bill Wendling991b84e2009-12-01 00:53:11 +0000852define void @foo() nounwind ssp {
Jim Laskey14edc932006-03-14 18:08:46 +0000853entry:
Bill Wendling05252352009-12-01 00:59:58 +0000854 %X = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
855 %Y = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
856 %Z = alloca i32, align 4 ; &lt;i32*&gt; [#uses=3]
857 %0 = bitcast i32* %X to { }* ; &lt;{ }*&gt; [#uses=1]
Devang Patel4da997b2009-11-25 23:28:01 +0000858 call void @llvm.dbg.declare({ }* %0, metadata !0), !dbg !7
859 store i32 21, i32* %X, !dbg !8
Bill Wendling05252352009-12-01 00:59:58 +0000860 %1 = bitcast i32* %Y to { }* ; &lt;{ }*&gt; [#uses=1]
Devang Patel4da997b2009-11-25 23:28:01 +0000861 call void @llvm.dbg.declare({ }* %1, metadata !9), !dbg !10
862 store i32 22, i32* %Y, !dbg !11
Bill Wendling05252352009-12-01 00:59:58 +0000863 %2 = bitcast i32* %Z to { }* ; &lt;{ }*&gt; [#uses=1]
Devang Patel4da997b2009-11-25 23:28:01 +0000864 call void @llvm.dbg.declare({ }* %2, metadata !12), !dbg !14
865 store i32 23, i32* %Z, !dbg !15
Bill Wendling05252352009-12-01 00:59:58 +0000866 %tmp = load i32* %X, !dbg !16 ; &lt;i32&gt; [#uses=1]
867 %tmp1 = load i32* %Y, !dbg !16 ; &lt;i32&gt; [#uses=1]
868 %add = add nsw i32 %tmp, %tmp1, !dbg !16 ; &lt;i32&gt; [#uses=1]
Devang Patel4da997b2009-11-25 23:28:01 +0000869 store i32 %add, i32* %Z, !dbg !16
Bill Wendling05252352009-12-01 00:59:58 +0000870 %tmp2 = load i32* %Y, !dbg !17 ; &lt;i32&gt; [#uses=1]
Devang Patel4da997b2009-11-25 23:28:01 +0000871 store i32 %tmp2, i32* %X, !dbg !17
872 ret void, !dbg !18
Chris Lattner1811fca2004-01-05 05:06:33 +0000873}
Devang Patel4da997b2009-11-25 23:28:01 +0000874
875declare void @llvm.dbg.declare({ }*, metadata) nounwind readnone
876
877!0 = metadata !{i32 459008, metadata !1, metadata !"X",
878 metadata !3, i32 2, metadata !6}; [ DW_TAG_auto_variable ]
879!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
880!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo", metadata !"foo",
881 metadata !"foo", metadata !3, i32 1, metadata !4,
882 i1 false, i1 true}; [DW_TAG_subprogram ]
883!3 = metadata !{i32 458769, i32 0, i32 12, metadata !"foo.c",
884 metadata !"/private/tmp", metadata !"clang 1.1", i1 true,
885 i1 false, metadata !"", i32 0}; [DW_TAG_compile_unit ]
886!4 = metadata !{i32 458773, metadata !3, metadata !"", null, i32 0, i64 0, i64 0,
887 i64 0, i32 0, null, metadata !5, i32 0}; [DW_TAG_subroutine_type ]
888!5 = metadata !{null}
889!6 = metadata !{i32 458788, metadata !3, metadata !"int", metadata !3, i32 0,
890 i64 32, i64 32, i64 0, i32 0, i32 5}; [DW_TAG_base_type ]
891!7 = metadata !{i32 2, i32 7, metadata !1, null}
892!8 = metadata !{i32 2, i32 3, metadata !1, null}
893!9 = metadata !{i32 459008, metadata !1, metadata !"Y", metadata !3, i32 3,
894 metadata !6}; [ DW_TAG_auto_variable ]
895!10 = metadata !{i32 3, i32 7, metadata !1, null}
896!11 = metadata !{i32 3, i32 3, metadata !1, null}
897!12 = metadata !{i32 459008, metadata !13, metadata !"Z", metadata !3, i32 5,
898 metadata !6}; [ DW_TAG_auto_variable ]
899!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
900!14 = metadata !{i32 5, i32 9, metadata !13, null}
901!15 = metadata !{i32 5, i32 5, metadata !13, null}
902!16 = metadata !{i32 6, i32 5, metadata !13, null}
903!17 = metadata !{i32 8, i32 3, metadata !1, null}
904!18 = metadata !{i32 9, i32 1, metadata !2, null}
Misha Brukmanf91d9942004-05-12 19:21:57 +0000905</pre>
Chris Lattner1811fca2004-01-05 05:06:33 +0000906</div>
907
Bill Wendling991b84e2009-12-01 00:53:11 +0000908<p>This example illustrates a few important details about LLVM debugging
909 information. In particular, it shows how the <tt>llvm.dbg.declare</tt>
910 intrinsic and location information, which are attached to an instruction,
911 are applied together to allow a debugger to analyze the relationship between
912 statements, variable definitions, and the code used to implement the
913 function.</p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000914
Bill Wendling991b84e2009-12-01 00:53:11 +0000915<div class="doc_code">
Bill Wendling05252352009-12-01 00:59:58 +0000916<pre>
Bill Wendling991b84e2009-12-01 00:53:11 +0000917call void @llvm.dbg.declare({ }* %0, metadata !0), !dbg !7
918</pre>
919</div>
920
921<p>The first intrinsic
Devang Patel4da997b2009-11-25 23:28:01 +0000922 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Bill Wendling991b84e2009-12-01 00:53:11 +0000923 encodes debugging information for the variable <tt>X</tt>. The metadata
924 <tt>!dbg !7</tt> attached to the intrinsic provides scope information for the
925 variable <tt>X</tt>.</p>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000926
Bill Wendling991b84e2009-12-01 00:53:11 +0000927<div class="doc_code">
928<pre>
929!7 = metadata !{i32 2, i32 7, metadata !1, null}
930!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
931!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo",
932 metadata !"foo", metadata !"foo", metadata !3, i32 1,
933 metadata !4, i1 false, i1 true}; [DW_TAG_subprogram ]
934</pre>
935</div>
936
937<p>Here <tt>!7</tt> is metadata providing location information. It has four
938 fields: line number, column number, scope, and original scope. The original
939 scope represents inline location if this instruction is inlined inside a
940 caller, and is null otherwise. In this example, scope is encoded by
Devang Patel4da997b2009-11-25 23:28:01 +0000941 <tt>!1</tt>. <tt>!1</tt> represents a lexical block inside the scope
942 <tt>!2</tt>, where <tt>!2</tt> is a
Bill Wendling991b84e2009-12-01 00:53:11 +0000943 <a href="#format_subprograms">subprogram descriptor</a>. This way the
944 location information attached to the intrinsics indicates that the
945 variable <tt>X</tt> is declared at line number 2 at a function level scope in
946 function <tt>foo</tt>.</p>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000947
Devang Patel4da997b2009-11-25 23:28:01 +0000948<p>Now lets take another example.</p>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000949
Bill Wendling991b84e2009-12-01 00:53:11 +0000950<div class="doc_code">
Bill Wendling05252352009-12-01 00:59:58 +0000951<pre>
Bill Wendling991b84e2009-12-01 00:53:11 +0000952call void @llvm.dbg.declare({ }* %2, metadata !12), !dbg !14
953</pre>
954</div>
955
956<p>The second intrinsic
Devang Patel4da997b2009-11-25 23:28:01 +0000957 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Bill Wendling991b84e2009-12-01 00:53:11 +0000958 encodes debugging information for variable <tt>Z</tt>. The metadata
959 <tt>!dbg !14</tt> attached to the intrinsic provides scope information for
960 the variable <tt>Z</tt>.</p>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000961
Bill Wendling991b84e2009-12-01 00:53:11 +0000962<div class="doc_code">
963<pre>
964!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
965!14 = metadata !{i32 5, i32 9, metadata !13, null}
966</pre>
967</div>
Bill Wendlinge9353d72009-05-17 05:52:39 +0000968
John Criswell2a4b0802010-03-17 15:01:50 +0000969<p>Here <tt>!14</tt> indicates that <tt>Z</tt> is declared at line number 5 and
Bill Wendling991b84e2009-12-01 00:53:11 +0000970 column number 9 inside of lexical scope <tt>!13</tt>. The lexical scope
971 itself resides inside of lexical scope <tt>!1</tt> described above.</p>
972
973<p>The scope information attached with each instruction provides a
974 straightforward way to find instructions covered by a scope.</p>
975
Bill Wendlinge9353d72009-05-17 05:52:39 +0000976</div>
Chris Lattner1811fca2004-01-05 05:06:33 +0000977
978<!-- *********************************************************************** -->
979<div class="doc_section">
Chris Lattner941515c2004-01-06 05:31:32 +0000980 <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
Chris Lattner1811fca2004-01-05 05:06:33 +0000981</div>
Misha Brukmancda6a9b2004-12-09 20:27:37 +0000982<!-- *********************************************************************** -->
Chris Lattner1811fca2004-01-05 05:06:33 +0000983
984<div class="doc_text">
985
Misha Brukmanf91d9942004-05-12 19:21:57 +0000986<p>The C and C++ front-ends represent information about the program in a format
Bill Wendlinge9353d72009-05-17 05:52:39 +0000987 that is effectively identical
988 to <a href="http://www.eagercon.com/dwarf/dwarf3std.htm">DWARF 3.0</a> in
989 terms of information content. This allows code generators to trivially
990 support native debuggers by generating standard dwarf information, and
991 contains enough information for non-dwarf targets to translate it as
992 needed.</p>
Chris Lattner1811fca2004-01-05 05:06:33 +0000993
Jim Laskey14edc932006-03-14 18:08:46 +0000994<p>This section describes the forms used to represent C and C++ programs. Other
Bill Wendlinge9353d72009-05-17 05:52:39 +0000995 languages could pattern themselves after this (which itself is tuned to
996 representing programs in the same way that DWARF 3 does), or they could
997 choose to provide completely different forms if they don't fit into the DWARF
998 model. As support for debugging information gets added to the various LLVM
999 source-language front-ends, the information used should be documented
1000 here.</p>
Chris Lattner1811fca2004-01-05 05:06:33 +00001001
Jim Laskey14edc932006-03-14 18:08:46 +00001002<p>The following sections provide examples of various C/C++ constructs and the
Bill Wendlinge9353d72009-05-17 05:52:39 +00001003 debug information that would best describe those constructs.</p>
Jim Laskey14edc932006-03-14 18:08:46 +00001004
Chris Lattner1811fca2004-01-05 05:06:33 +00001005</div>
1006
1007<!-- ======================================================================= -->
1008<div class="doc_subsection">
Jim Laskey14edc932006-03-14 18:08:46 +00001009 <a name="ccxx_compile_units">C/C++ source file information</a>
Chris Lattner1811fca2004-01-05 05:06:33 +00001010</div>
1011
1012<div class="doc_text">
Chris Lattner1811fca2004-01-05 05:06:33 +00001013
Bill Wendlinge9353d72009-05-17 05:52:39 +00001014<p>Given the source files <tt>MySource.cpp</tt> and <tt>MyHeader.h</tt> located
1015 in the directory <tt>/Users/mine/sources</tt>, the following code:</p>
Chris Lattner941515c2004-01-06 05:31:32 +00001016
Bill Wendlinge9353d72009-05-17 05:52:39 +00001017<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001018<pre>
1019#include "MyHeader.h"
Chris Lattner941515c2004-01-06 05:31:32 +00001020
Jim Laskey14edc932006-03-14 18:08:46 +00001021int main(int argc, char *argv[]) {
1022 return 0;
1023}
1024</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001025</div>
Chris Lattner941515c2004-01-06 05:31:32 +00001026
Misha Brukman39dcddf2008-12-16 02:54:22 +00001027<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskey14edc932006-03-14 18:08:46 +00001028
Bill Wendlinge9353d72009-05-17 05:52:39 +00001029<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001030<pre>
1031...
1032;;
Devang Patel59445db2010-03-09 00:44:10 +00001033;; Define the compile unit for the main source file "/Users/mine/sources/MySource.cpp".
Jim Laskey14edc932006-03-14 18:08:46 +00001034;;
Devang Patel59445db2010-03-09 00:44:10 +00001035!2 = metadata !{
1036 i32 524305, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001037 i32 0, ;; Unused
1038 i32 4, ;; Language Id
1039 metadata !"MySource.cpp",
1040 metadata !"/Users/mine/sources",
1041 metadata !"4.2.1 (Based on Apple Inc. build 5649) (LLVM build 00)",
1042 i1 true, ;; Main Compile Unit
1043 i1 false, ;; Optimized compile unit
1044 metadata !"", ;; Compiler flags
1045 i32 0} ;; Runtime version
1046
Jim Laskey14edc932006-03-14 18:08:46 +00001047;;
Devang Patel59445db2010-03-09 00:44:10 +00001048;; Define the file for the file "/Users/mine/sources/MySource.cpp".
Jim Laskey14edc932006-03-14 18:08:46 +00001049;;
Devang Patel80ae3492009-08-28 23:24:31 +00001050!1 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001051 i32 524329, ;; Tag
1052 metadata !"MySource.cpp",
Devang Patel80ae3492009-08-28 23:24:31 +00001053 metadata !"/Users/mine/sources",
Devang Patel59445db2010-03-09 00:44:10 +00001054 metadata !3 ;; Compile unit
1055}
1056
1057;;
1058;; Define the file for the file "/Users/mine/sources/Myheader.h"
1059;;
1060!3 = metadata !{
1061 i32 524329, ;; Tag
1062 metadata !"Myheader.h"
1063 metadata !"/Users/mine/sources",
1064 metadata !3 ;; Compile unit
1065}
Jim Laskey14edc932006-03-14 18:08:46 +00001066
Jim Laskey14edc932006-03-14 18:08:46 +00001067...
1068</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001069</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001070
Devang Patel5bc1c4b2010-03-26 19:08:36 +00001071<p>llvm::Instruction provides easy access to metadata attached with an
1072instruction. One can extract line number information encoded in LLVM IR
1073using <tt>Instruction::getMetadata()</tt> and
1074<tt>DILocation::getLineNumber()</tt>.
1075<pre>
1076 if (MDNode *N = I->getMetadata("dbg")) { // Here I is an LLVM instruction
1077 DILocation Loc(N); // DILocation is in DebugInfo.h
1078 unsigned Line = Loc.getLineNumber();
1079 StringRef File = Loc.getFilename();
1080 StringRef Dir = Loc.getDirectory();
1081 }
1082</pre>
Chris Lattner941515c2004-01-06 05:31:32 +00001083</div>
1084
1085<!-- ======================================================================= -->
1086<div class="doc_subsection">
Jim Laskey14edc932006-03-14 18:08:46 +00001087 <a name="ccxx_global_variable">C/C++ global variable information</a>
Chris Lattner941515c2004-01-06 05:31:32 +00001088</div>
1089
1090<div class="doc_text">
Jim Laskey14edc932006-03-14 18:08:46 +00001091
Misha Brukman39dcddf2008-12-16 02:54:22 +00001092<p>Given an integer global variable declared as follows:</p>
Jim Laskey14edc932006-03-14 18:08:46 +00001093
Bill Wendlinge9353d72009-05-17 05:52:39 +00001094<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001095<pre>
1096int MyGlobal = 100;
1097</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001098</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001099
Misha Brukman39dcddf2008-12-16 02:54:22 +00001100<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskey14edc932006-03-14 18:08:46 +00001101
Bill Wendlinge9353d72009-05-17 05:52:39 +00001102<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001103<pre>
1104;;
Jim Laskey14edc932006-03-14 18:08:46 +00001105;; Define the global itself.
1106;;
1107%MyGlobal = global int 100
1108...
1109;;
Devang Patel80ae3492009-08-28 23:24:31 +00001110;; List of debug info of globals
Jim Laskey14edc932006-03-14 18:08:46 +00001111;;
Devang Patel80ae3492009-08-28 23:24:31 +00001112!llvm.dbg.gv = !{!0}
Jim Laskey14edc932006-03-14 18:08:46 +00001113
1114;;
1115;; Define the global variable descriptor. Note the reference to the global
1116;; variable anchor and the global variable itself.
1117;;
Devang Patel80ae3492009-08-28 23:24:31 +00001118!0 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001119 i32 524340, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001120 i32 0, ;; Unused
1121 metadata !1, ;; Context
1122 metadata !"MyGlobal", ;; Name
1123 metadata !"MyGlobal", ;; Display Name
1124 metadata !"MyGlobal", ;; Linkage Name
Devang Patel59445db2010-03-09 00:44:10 +00001125 metadata !3, ;; Compile Unit
Devang Patel80ae3492009-08-28 23:24:31 +00001126 i32 1, ;; Line Number
Devang Patel59445db2010-03-09 00:44:10 +00001127 metadata !4, ;; Type
Devang Patel80ae3492009-08-28 23:24:31 +00001128 i1 false, ;; Is a local variable
1129 i1 true, ;; Is this a definition
1130 i32* @MyGlobal ;; The global variable
1131}
1132
Jim Laskey14edc932006-03-14 18:08:46 +00001133;;
1134;; Define the basic type of 32 bit signed integer. Note that since int is an
1135;; intrinsic type the source file is NULL and line 0.
1136;;
Devang Patel59445db2010-03-09 00:44:10 +00001137!4 = metadata !{
1138 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001139 metadata !1, ;; Context
1140 metadata !"int", ;; Name
Devang Patel59445db2010-03-09 00:44:10 +00001141 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001142 i32 0, ;; Line number
1143 i64 32, ;; Size in Bits
1144 i64 32, ;; Align in Bits
1145 i64 0, ;; Offset in Bits
1146 i32 0, ;; Flags
1147 i32 5 ;; Encoding
1148}
Jim Laskey14edc932006-03-14 18:08:46 +00001149
Jim Laskey14edc932006-03-14 18:08:46 +00001150</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001151</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001152
Chris Lattner941515c2004-01-06 05:31:32 +00001153</div>
Chris Lattner1811fca2004-01-05 05:06:33 +00001154
Jim Laskey14edc932006-03-14 18:08:46 +00001155<!-- ======================================================================= -->
1156<div class="doc_subsection">
1157 <a name="ccxx_subprogram">C/C++ function information</a>
1158</div>
1159
1160<div class="doc_text">
1161
Misha Brukman39dcddf2008-12-16 02:54:22 +00001162<p>Given a function declared as follows:</p>
Jim Laskey14edc932006-03-14 18:08:46 +00001163
Bill Wendlinge9353d72009-05-17 05:52:39 +00001164<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001165<pre>
1166int main(int argc, char *argv[]) {
1167 return 0;
1168}
1169</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001170</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001171
Misha Brukman39dcddf2008-12-16 02:54:22 +00001172<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskey14edc932006-03-14 18:08:46 +00001173
Bill Wendlinge9353d72009-05-17 05:52:39 +00001174<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001175<pre>
1176;;
Jim Laskey14edc932006-03-14 18:08:46 +00001177;; Define the anchor for subprograms. Note that the second field of the
1178;; anchor is 46, which is the same as the tag for subprograms
1179;; (46 = DW_TAG_subprogram.)
1180;;
Devang Patel59445db2010-03-09 00:44:10 +00001181!6 = metadata !{
1182 i32 524334, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001183 i32 0, ;; Unused
1184 metadata !1, ;; Context
1185 metadata !"main", ;; Name
1186 metadata !"main", ;; Display name
1187 metadata !"main", ;; Linkage name
Devang Patel59445db2010-03-09 00:44:10 +00001188 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001189 i32 1, ;; Line number
Devang Patel59445db2010-03-09 00:44:10 +00001190 metadata !4, ;; Type
Devang Patel80ae3492009-08-28 23:24:31 +00001191 i1 false, ;; Is local
1192 i1 true ;; Is definition
1193}
Jim Laskey14edc932006-03-14 18:08:46 +00001194;;
1195;; Define the subprogram itself.
1196;;
Devang Patel80ae3492009-08-28 23:24:31 +00001197define i32 @main(i32 %argc, i8** %argv) {
Jim Laskey14edc932006-03-14 18:08:46 +00001198...
1199}
1200</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001201</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001202
1203</div>
1204
1205<!-- ======================================================================= -->
1206<div class="doc_subsection">
1207 <a name="ccxx_basic_types">C/C++ basic types</a>
1208</div>
1209
1210<div class="doc_text">
1211
Misha Brukman39dcddf2008-12-16 02:54:22 +00001212<p>The following are the basic type descriptors for C/C++ core types:</p>
Jim Laskey14edc932006-03-14 18:08:46 +00001213
1214</div>
1215
1216<!-- ======================================================================= -->
1217<div class="doc_subsubsection">
1218 <a name="ccxx_basic_type_bool">bool</a>
1219</div>
1220
1221<div class="doc_text">
1222
Bill Wendlinge9353d72009-05-17 05:52:39 +00001223<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001224<pre>
Devang Patel80ae3492009-08-28 23:24:31 +00001225!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001226 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001227 metadata !1, ;; Context
1228 metadata !"bool", ;; Name
Devang Patel59445db2010-03-09 00:44:10 +00001229 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001230 i32 0, ;; Line number
1231 i64 8, ;; Size in Bits
1232 i64 8, ;; Align in Bits
1233 i64 0, ;; Offset in Bits
1234 i32 0, ;; Flags
1235 i32 2 ;; Encoding
1236}
Jim Laskey14edc932006-03-14 18:08:46 +00001237</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001238</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001239
1240</div>
1241
1242<!-- ======================================================================= -->
1243<div class="doc_subsubsection">
1244 <a name="ccxx_basic_char">char</a>
1245</div>
1246
1247<div class="doc_text">
1248
Bill Wendlinge9353d72009-05-17 05:52:39 +00001249<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001250<pre>
Devang Patel80ae3492009-08-28 23:24:31 +00001251!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001252 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001253 metadata !1, ;; Context
1254 metadata !"char", ;; Name
Devang Patel59445db2010-03-09 00:44:10 +00001255 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001256 i32 0, ;; Line number
1257 i64 8, ;; Size in Bits
1258 i64 8, ;; Align in Bits
1259 i64 0, ;; Offset in Bits
1260 i32 0, ;; Flags
1261 i32 6 ;; Encoding
1262}
Jim Laskey14edc932006-03-14 18:08:46 +00001263</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001264</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001265
1266</div>
1267
1268<!-- ======================================================================= -->
1269<div class="doc_subsubsection">
1270 <a name="ccxx_basic_unsigned_char">unsigned char</a>
1271</div>
1272
1273<div class="doc_text">
1274
Bill Wendlinge9353d72009-05-17 05:52:39 +00001275<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001276<pre>
Devang Patel80ae3492009-08-28 23:24:31 +00001277!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001278 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001279 metadata !1, ;; Context
1280 metadata !"unsigned char",
Devang Patel59445db2010-03-09 00:44:10 +00001281 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001282 i32 0, ;; Line number
1283 i64 8, ;; Size in Bits
1284 i64 8, ;; Align in Bits
1285 i64 0, ;; Offset in Bits
1286 i32 0, ;; Flags
1287 i32 8 ;; Encoding
1288}
Jim Laskey14edc932006-03-14 18:08:46 +00001289</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001290</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001291
1292</div>
1293
1294<!-- ======================================================================= -->
1295<div class="doc_subsubsection">
1296 <a name="ccxx_basic_short">short</a>
1297</div>
1298
1299<div class="doc_text">
1300
Bill Wendlinge9353d72009-05-17 05:52:39 +00001301<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001302<pre>
Devang Patel80ae3492009-08-28 23:24:31 +00001303!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001304 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001305 metadata !1, ;; Context
1306 metadata !"short int",
Devang Patel59445db2010-03-09 00:44:10 +00001307 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001308 i32 0, ;; Line number
1309 i64 16, ;; Size in Bits
1310 i64 16, ;; Align in Bits
1311 i64 0, ;; Offset in Bits
1312 i32 0, ;; Flags
1313 i32 5 ;; Encoding
1314}
Jim Laskey14edc932006-03-14 18:08:46 +00001315</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001316</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001317
1318</div>
1319
1320<!-- ======================================================================= -->
1321<div class="doc_subsubsection">
1322 <a name="ccxx_basic_unsigned_short">unsigned short</a>
1323</div>
1324
1325<div class="doc_text">
1326
Bill Wendlinge9353d72009-05-17 05:52:39 +00001327<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001328<pre>
Devang Patel80ae3492009-08-28 23:24:31 +00001329!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001330 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001331 metadata !1, ;; Context
1332 metadata !"short unsigned int",
Devang Patel59445db2010-03-09 00:44:10 +00001333 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001334 i32 0, ;; Line number
1335 i64 16, ;; Size in Bits
1336 i64 16, ;; Align in Bits
1337 i64 0, ;; Offset in Bits
1338 i32 0, ;; Flags
1339 i32 7 ;; Encoding
1340}
Jim Laskey14edc932006-03-14 18:08:46 +00001341</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001342</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001343
1344</div>
1345
1346<!-- ======================================================================= -->
1347<div class="doc_subsubsection">
1348 <a name="ccxx_basic_int">int</a>
1349</div>
1350
1351<div class="doc_text">
1352
Bill Wendlinge9353d72009-05-17 05:52:39 +00001353<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001354<pre>
Devang Patel80ae3492009-08-28 23:24:31 +00001355!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001356 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001357 metadata !1, ;; Context
1358 metadata !"int", ;; Name
Devang Patel59445db2010-03-09 00:44:10 +00001359 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001360 i32 0, ;; Line number
1361 i64 32, ;; Size in Bits
1362 i64 32, ;; Align in Bits
1363 i64 0, ;; Offset in Bits
1364 i32 0, ;; Flags
1365 i32 5 ;; Encoding
1366}
Bill Wendlinge9353d72009-05-17 05:52:39 +00001367</pre></div>
Jim Laskey14edc932006-03-14 18:08:46 +00001368
1369</div>
1370
1371<!-- ======================================================================= -->
1372<div class="doc_subsubsection">
1373 <a name="ccxx_basic_unsigned_int">unsigned int</a>
1374</div>
1375
1376<div class="doc_text">
1377
Bill Wendlinge9353d72009-05-17 05:52:39 +00001378<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001379<pre>
Devang Patel80ae3492009-08-28 23:24:31 +00001380!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001381 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001382 metadata !1, ;; Context
1383 metadata !"unsigned int",
Devang Patel59445db2010-03-09 00:44:10 +00001384 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001385 i32 0, ;; Line number
1386 i64 32, ;; Size in Bits
1387 i64 32, ;; Align in Bits
1388 i64 0, ;; Offset in Bits
1389 i32 0, ;; Flags
1390 i32 7 ;; Encoding
1391}
Jim Laskey14edc932006-03-14 18:08:46 +00001392</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001393</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001394
1395</div>
1396
1397<!-- ======================================================================= -->
1398<div class="doc_subsubsection">
1399 <a name="ccxx_basic_long_long">long long</a>
1400</div>
1401
1402<div class="doc_text">
1403
Bill Wendlinge9353d72009-05-17 05:52:39 +00001404<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001405<pre>
Devang Patel80ae3492009-08-28 23:24:31 +00001406!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001407 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001408 metadata !1, ;; Context
1409 metadata !"long long int",
Devang Patel59445db2010-03-09 00:44:10 +00001410 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001411 i32 0, ;; Line number
1412 i64 64, ;; Size in Bits
1413 i64 64, ;; Align in Bits
1414 i64 0, ;; Offset in Bits
1415 i32 0, ;; Flags
1416 i32 5 ;; Encoding
1417}
Jim Laskey14edc932006-03-14 18:08:46 +00001418</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001419</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001420
1421</div>
1422
1423<!-- ======================================================================= -->
1424<div class="doc_subsubsection">
1425 <a name="ccxx_basic_unsigned_long_long">unsigned long long</a>
1426</div>
1427
1428<div class="doc_text">
1429
Bill Wendlinge9353d72009-05-17 05:52:39 +00001430<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001431<pre>
Devang Patel80ae3492009-08-28 23:24:31 +00001432!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001433 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001434 metadata !1, ;; Context
1435 metadata !"long long unsigned int",
Devang Patel59445db2010-03-09 00:44:10 +00001436 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001437 i32 0, ;; Line number
1438 i64 64, ;; Size in Bits
1439 i64 64, ;; Align in Bits
1440 i64 0, ;; Offset in Bits
1441 i32 0, ;; Flags
1442 i32 7 ;; Encoding
1443}
Jim Laskey14edc932006-03-14 18:08:46 +00001444</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001445</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001446
1447</div>
1448
1449<!-- ======================================================================= -->
1450<div class="doc_subsubsection">
1451 <a name="ccxx_basic_float">float</a>
1452</div>
1453
1454<div class="doc_text">
1455
Bill Wendlinge9353d72009-05-17 05:52:39 +00001456<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001457<pre>
Devang Patel80ae3492009-08-28 23:24:31 +00001458!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001459 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001460 metadata !1, ;; Context
1461 metadata !"float",
Devang Patel59445db2010-03-09 00:44:10 +00001462 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001463 i32 0, ;; Line number
1464 i64 32, ;; Size in Bits
1465 i64 32, ;; Align in Bits
1466 i64 0, ;; Offset in Bits
1467 i32 0, ;; Flags
1468 i32 4 ;; Encoding
1469}
Jim Laskey14edc932006-03-14 18:08:46 +00001470</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001471</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001472
1473</div>
1474
1475<!-- ======================================================================= -->
1476<div class="doc_subsubsection">
1477 <a name="ccxx_basic_double">double</a>
1478</div>
1479
1480<div class="doc_text">
1481
Bill Wendlinge9353d72009-05-17 05:52:39 +00001482<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001483<pre>
Devang Patel80ae3492009-08-28 23:24:31 +00001484!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001485 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001486 metadata !1, ;; Context
1487 metadata !"double",;; Name
Devang Patel59445db2010-03-09 00:44:10 +00001488 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001489 i32 0, ;; Line number
1490 i64 64, ;; Size in Bits
1491 i64 64, ;; Align in Bits
1492 i64 0, ;; Offset in Bits
1493 i32 0, ;; Flags
1494 i32 4 ;; Encoding
1495}
Jim Laskey14edc932006-03-14 18:08:46 +00001496</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001497</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001498
1499</div>
1500
1501<!-- ======================================================================= -->
1502<div class="doc_subsection">
1503 <a name="ccxx_derived_types">C/C++ derived types</a>
1504</div>
1505
1506<div class="doc_text">
1507
Misha Brukman39dcddf2008-12-16 02:54:22 +00001508<p>Given the following as an example of C/C++ derived type:</p>
Jim Laskey14edc932006-03-14 18:08:46 +00001509
Bill Wendlinge9353d72009-05-17 05:52:39 +00001510<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001511<pre>
1512typedef const int *IntPtr;
1513</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001514</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001515
Misha Brukman39dcddf2008-12-16 02:54:22 +00001516<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskey14edc932006-03-14 18:08:46 +00001517
Bill Wendlinge9353d72009-05-17 05:52:39 +00001518<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001519<pre>
1520;;
1521;; Define the typedef "IntPtr".
1522;;
Devang Patel80ae3492009-08-28 23:24:31 +00001523!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001524 i32 524310, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001525 metadata !1, ;; Context
1526 metadata !"IntPtr", ;; Name
Devang Patel59445db2010-03-09 00:44:10 +00001527 metadata !3, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001528 i32 0, ;; Line number
1529 i64 0, ;; Size in bits
1530 i64 0, ;; Align in bits
1531 i64 0, ;; Offset in bits
1532 i32 0, ;; Flags
1533 metadata !4 ;; Derived From type
1534}
Jim Laskey14edc932006-03-14 18:08:46 +00001535
1536;;
1537;; Define the pointer type.
1538;;
Devang Patel80ae3492009-08-28 23:24:31 +00001539!4 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001540 i32 524303, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001541 metadata !1, ;; Context
1542 metadata !"", ;; Name
Devang Patel59445db2010-03-09 00:44:10 +00001543 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001544 i32 0, ;; Line number
1545 i64 64, ;; Size in bits
1546 i64 64, ;; Align in bits
1547 i64 0, ;; Offset in bits
1548 i32 0, ;; Flags
1549 metadata !5 ;; Derived From type
1550}
Jim Laskey14edc932006-03-14 18:08:46 +00001551;;
1552;; Define the const type.
1553;;
Devang Patel80ae3492009-08-28 23:24:31 +00001554!5 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001555 i32 524326, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001556 metadata !1, ;; Context
1557 metadata !"", ;; Name
Devang Patel59445db2010-03-09 00:44:10 +00001558 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001559 i32 0, ;; Line number
1560 i64 32, ;; Size in bits
1561 i64 32, ;; Align in bits
1562 i64 0, ;; Offset in bits
1563 i32 0, ;; Flags
1564 metadata !6 ;; Derived From type
1565}
Jim Laskey14edc932006-03-14 18:08:46 +00001566;;
1567;; Define the int type.
1568;;
Devang Patel80ae3492009-08-28 23:24:31 +00001569!6 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001570 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001571 metadata !1, ;; Context
1572 metadata !"int", ;; Name
Devang Patel59445db2010-03-09 00:44:10 +00001573 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001574 i32 0, ;; Line number
1575 i64 32, ;; Size in bits
1576 i64 32, ;; Align in bits
1577 i64 0, ;; Offset in bits
1578 i32 0, ;; Flags
1579 5 ;; Encoding
1580}
Jim Laskey14edc932006-03-14 18:08:46 +00001581</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001582</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001583
1584</div>
1585
1586<!-- ======================================================================= -->
1587<div class="doc_subsection">
1588 <a name="ccxx_composite_types">C/C++ struct/union types</a>
1589</div>
1590
1591<div class="doc_text">
1592
Misha Brukman39dcddf2008-12-16 02:54:22 +00001593<p>Given the following as an example of C/C++ struct type:</p>
Jim Laskey14edc932006-03-14 18:08:46 +00001594
Bill Wendlinge9353d72009-05-17 05:52:39 +00001595<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001596<pre>
1597struct Color {
1598 unsigned Red;
1599 unsigned Green;
1600 unsigned Blue;
1601};
1602</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001603</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001604
Misha Brukman39dcddf2008-12-16 02:54:22 +00001605<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskey14edc932006-03-14 18:08:46 +00001606
Bill Wendlinge9353d72009-05-17 05:52:39 +00001607<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001608<pre>
1609;;
1610;; Define basic type for unsigned int.
1611;;
Devang Patel80ae3492009-08-28 23:24:31 +00001612!5 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001613 i32 524324, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001614 metadata !1, ;; Context
1615 metadata !"unsigned int",
Devang Patel59445db2010-03-09 00:44:10 +00001616 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001617 i32 0, ;; Line number
1618 i64 32, ;; Size in Bits
1619 i64 32, ;; Align in Bits
1620 i64 0, ;; Offset in Bits
1621 i32 0, ;; Flags
1622 i32 7 ;; Encoding
1623}
Jim Laskey14edc932006-03-14 18:08:46 +00001624;;
1625;; Define composite type for struct Color.
1626;;
Devang Patel80ae3492009-08-28 23:24:31 +00001627!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001628 i32 524307, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001629 metadata !1, ;; Context
1630 metadata !"Color", ;; Name
1631 metadata !1, ;; Compile unit
1632 i32 1, ;; Line number
1633 i64 96, ;; Size in bits
1634 i64 32, ;; Align in bits
1635 i64 0, ;; Offset in bits
1636 i32 0, ;; Flags
1637 null, ;; Derived From
1638 metadata !3, ;; Elements
1639 i32 0 ;; Runtime Language
1640}
Jim Laskey14edc932006-03-14 18:08:46 +00001641
1642;;
1643;; Define the Red field.
1644;;
Devang Patel80ae3492009-08-28 23:24:31 +00001645!4 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001646 i32 524301, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001647 metadata !1, ;; Context
1648 metadata !"Red", ;; Name
Devang Patel59445db2010-03-09 00:44:10 +00001649 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001650 i32 2, ;; Line number
1651 i64 32, ;; Size in bits
1652 i64 32, ;; Align in bits
1653 i64 0, ;; Offset in bits
1654 i32 0, ;; Flags
1655 metadata !5 ;; Derived From type
1656}
Jim Laskey14edc932006-03-14 18:08:46 +00001657
1658;;
1659;; Define the Green field.
1660;;
Devang Patel80ae3492009-08-28 23:24:31 +00001661!6 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001662 i32 524301, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001663 metadata !1, ;; Context
1664 metadata !"Green", ;; Name
Devang Patel59445db2010-03-09 00:44:10 +00001665 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001666 i32 3, ;; Line number
1667 i64 32, ;; Size in bits
1668 i64 32, ;; Align in bits
1669 i64 32, ;; Offset in bits
1670 i32 0, ;; Flags
1671 metadata !5 ;; Derived From type
1672}
Jim Laskey14edc932006-03-14 18:08:46 +00001673
1674;;
1675;; Define the Blue field.
1676;;
Devang Patel80ae3492009-08-28 23:24:31 +00001677!7 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001678 i32 524301, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001679 metadata !1, ;; Context
1680 metadata !"Blue", ;; Name
Devang Patel59445db2010-03-09 00:44:10 +00001681 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001682 i32 4, ;; Line number
1683 i64 32, ;; Size in bits
1684 i64 32, ;; Align in bits
1685 i64 64, ;; Offset in bits
1686 i32 0, ;; Flags
1687 metadata !5 ;; Derived From type
1688}
Jim Laskey14edc932006-03-14 18:08:46 +00001689
1690;;
1691;; Define the array of fields used by the composite type Color.
1692;;
Devang Patel80ae3492009-08-28 23:24:31 +00001693!3 = metadata !{metadata !4, metadata !6, metadata !7}
Jim Laskey14edc932006-03-14 18:08:46 +00001694</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001695</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001696
1697</div>
1698
1699<!-- ======================================================================= -->
1700<div class="doc_subsection">
1701 <a name="ccxx_enumeration_types">C/C++ enumeration types</a>
1702</div>
1703
1704<div class="doc_text">
1705
Misha Brukman39dcddf2008-12-16 02:54:22 +00001706<p>Given the following as an example of C/C++ enumeration type:</p>
Jim Laskey14edc932006-03-14 18:08:46 +00001707
Bill Wendlinge9353d72009-05-17 05:52:39 +00001708<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001709<pre>
1710enum Trees {
1711 Spruce = 100,
1712 Oak = 200,
1713 Maple = 300
1714};
1715</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001716</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001717
Misha Brukman39dcddf2008-12-16 02:54:22 +00001718<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskey14edc932006-03-14 18:08:46 +00001719
Bill Wendlinge9353d72009-05-17 05:52:39 +00001720<div class="doc_code">
Jim Laskey14edc932006-03-14 18:08:46 +00001721<pre>
1722;;
1723;; Define composite type for enum Trees
1724;;
Devang Patel80ae3492009-08-28 23:24:31 +00001725!2 = metadata !{
Devang Patel59445db2010-03-09 00:44:10 +00001726 i32 524292, ;; Tag
Devang Patel80ae3492009-08-28 23:24:31 +00001727 metadata !1, ;; Context
1728 metadata !"Trees", ;; Name
Devang Patel59445db2010-03-09 00:44:10 +00001729 metadata !1, ;; File
Devang Patel80ae3492009-08-28 23:24:31 +00001730 i32 1, ;; Line number
1731 i64 32, ;; Size in bits
1732 i64 32, ;; Align in bits
1733 i64 0, ;; Offset in bits
1734 i32 0, ;; Flags
1735 null, ;; Derived From type
1736 metadata !3, ;; Elements
1737 i32 0 ;; Runtime language
1738}
Devang Patel02aac922009-08-25 05:24:07 +00001739
Devang Patelf08e35d2009-08-26 05:01:18 +00001740;;
1741;; Define the array of enumerators used by composite type Trees.
1742;;
Devang Patel80ae3492009-08-28 23:24:31 +00001743!3 = metadata !{metadata !4, metadata !5, metadata !6}
1744
1745;;
1746;; Define Spruce enumerator.
1747;;
Devang Patel59445db2010-03-09 00:44:10 +00001748!4 = metadata !{i32 524328, metadata !"Spruce", i64 100}
Devang Patel80ae3492009-08-28 23:24:31 +00001749
1750;;
1751;; Define Oak enumerator.
1752;;
Devang Patel59445db2010-03-09 00:44:10 +00001753!5 = metadata !{i32 524328, metadata !"Oak", i64 200}
Devang Patel80ae3492009-08-28 23:24:31 +00001754
1755;;
1756;; Define Maple enumerator.
1757;;
Devang Patel59445db2010-03-09 00:44:10 +00001758!6 = metadata !{i32 524328, metadata !"Maple", i64 300}
Devang Patel80ae3492009-08-28 23:24:31 +00001759
Jim Laskey14edc932006-03-14 18:08:46 +00001760</pre>
Bill Wendlinge9353d72009-05-17 05:52:39 +00001761</div>
Jim Laskey14edc932006-03-14 18:08:46 +00001762
1763</div>
Chris Lattner1811fca2004-01-05 05:06:33 +00001764
1765<!-- *********************************************************************** -->
Misha Brukmanf91d9942004-05-12 19:21:57 +00001766
Chris Lattner1811fca2004-01-05 05:06:33 +00001767<hr>
Misha Brukmanf91d9942004-05-12 19:21:57 +00001768<address>
1769 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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Misha Brukmanf91d9942004-05-12 19:21:57 +00001773
1774 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencerca058542006-03-14 05:39:39 +00001775 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
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Misha Brukmanf91d9942004-05-12 19:21:57 +00001777</address>
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1779</body>
1780</html>